Wildlife watch Colder, darker days are hav­ing a but­ter­fly ef­fect

Scot­tish Wildlife Trust’s Falls of Clyde Wildlife Re­serve Ranger Laura Preston has spot­ted a num­ber of but­ter­flies on the re­serve.

It has been a strange week for but­ter­flies.

I’ve been see­ing red ad­mi­ral fly­ing about early in the morn­ing, cling­ing to the last of the warm sun­shine, but I’ve also seen a small tor­toise­shell, al­ready hun­kered down, hi­ber­nat­ing in one of our out­build­ings.

But­ter­flies and moths, un­like birds and mam­mals, rely on ex­ter­nal heat sources to warm their bod­ies enough so that they can be ac­tive.

This means, dur­ing the cooler months, they are un­able to move and are forced to re­main in­ac­tive.

Tech­ni­cally, in­sects don’t hi­ber­nate, rather they go into a state of dor­mancy.

The ma­jor­ity of but­ter­flies and moths will over­win­ter or hi­ber­nate in their lar­val stages (cater­pil­lars), fol­lowed by the pu­pae (chrysalis), eggs and lastly the adults. Five of our 59 res­i­dent species of but­ter­fly spend the win­ter as hi­ber­nat­ing adults, but the ones you are most likely to find hi­ber­nat­ing in your house are small tor­toise­shell and pea­cock.

Some species, like the painted lady, have evolved a com­pletely dif­fer­ent strat­egy for sur­viv­ing the win­ter months – they mi­grate to a warmer place, of­ten fly­ing thou­sands of miles in the process.

It is pos­si­ble to buy but­ter­fly hiber­na­tion boxes. My thoughts on that is this is one of those ‘wildlife gar­den­ing gim­micks’ sold to en­tice avid wildlife gar­den­ers, but the like­li­hood of them be­ing used are very slim.

Any hi­ber­nat­ing in­sect will need a con­stant cool tem­per­a­ture and there­fore a wooden box won’t re­ally be up to the job.

On any sunny day the tem­per­a­ture inside the box would heat up suf­fi­ciently to wake up any hi­ber­nat­ing but­ter­fly.

It is also worth not­ing that but­ter­flies aren’t stupid and they will choose a dark, cool, dry spot like an out­house, shed, garage, at­tic (etc).

If you do want to use one, make sure it is put in a south-fac­ing po­si­tion, in a shaded, dry place!

Hun­ker­ing down But­ter­flies, like this small tor­toise­shell, are pre­par­ing for win­ter